Remove empty /proc/device-tree when no openfirmware exists.

Remove empty /proc/device-tree when no openfirmware exists.

[Dave Jones]

distribution kernels might want to build in support for /proc/device-tree
for kernels that might end up running on hardware that doesn't support openfirmware.
This results in an empty /proc/device-tree existing.
Remove it if the OFW root node doesn't exist.

[This situation actually confuses grub2, resulting in install failures.
 grub2 sees the /proc/device-tree and picks the wrong install target
 cf. http://bzr.savannah.gnu.org/lh/grub/trunk/grub/annotate/4300/util/grub-install.in#L311
 grub should be more robust, but still, leaving an empty proc dir seems pointless. ]

Signed-off-by: Dave Jones <davej@redhat.com>

diff --git a/fs/proc/proc_devtree.c b/fs/proc/proc_devtree.c
index 927cbd1..f060f28 100644
--- a/fs/proc/proc_devtree.c
+++ b/fs/proc/proc_devtree.c
@@ -233,6 +233,7 @@ void __init proc_device_tree_init(void)
 		return;
 	root = of_find_node_by_path("/");
 	if (root == NULL) {
+		remove_proc_entry("device-tree", NULL);
 		pr_debug("/proc/device-tree: can't find root\n");
 		return;
 	}

Re: Remove empty /proc/device-tree when no openfirmware exists.

[Josh Boyer]

On Mon, May 14, 2012 at 12:41 PM, Dave Jones <davej@redhat.com> wrote:
> distribution kernels might want to build in support for /proc/device-tree
> for kernels that might end up running on hardware that doesn't support openfirmware.
> This results in an empty /proc/device-tree existing.
> Remove it if the OFW root node doesn't exist.
>
> [This situation actually confuses grub2, resulting in install failures.
>  grub2 sees the /proc/device-tree and picks the wrong install target
>  cf. http://bzr.savannah.gnu.org/lh/grub/trunk/grub/annotate/4300/util/grub-install.in#L311
>  grub should be more robust, but still, leaving an empty proc dir seems pointless. ]
>
> Signed-off-by: Dave Jones <davej@redhat.com>

We're still carrying this in Fedora for
https://bugzilla.redhat.com/show_bug.cgi?id=818378 .  Can we get this
upstream sometime soon?

josh

> diff --git a/fs/proc/proc_devtree.c b/fs/proc/proc_devtree.c
> index 927cbd1..f060f28 100644
> --- a/fs/proc/proc_devtree.c
> +++ b/fs/proc/proc_devtree.c
> @@ -233,6 +233,7 @@ void __init proc_device_tree_init(void)
>                 return;
>         root = of_find_node_by_path("/");
>         if (root == NULL) {
> +               remove_proc_entry("device-tree", NULL);
>                 pr_debug("/proc/device-tree: can't find root\n");
>                 return;
>         }
> --
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